Guidewire

ABSTRACT

A guidewire comprising a hydrophilic surface coating encasing a core and a metal coil along a longitudinal length of the hydrophilic surface coating to form a distal closed tip, the metal coil circumscribing the core along a predetermined length, the core extending longitudinally beyond the metal coil in both a proximal direction and a distal direction, wherein a proximal section of the guidewire includes a hydrophobic surface coating.

INTRODUCTION TO THE INVENTION

The present disclosure is directed to guidewires, as well as method offabricating and use the same. Guidewires are used in the art foraccessing and navigating tortuous bodily lumens as part of a medicalprocedure. For example, a guidewire may be used to access and navigateurinary tracts. After arriving at the intended location within the bodylumen, further surgical device may be inserted in to the lumen using theguidewire as a track along which the further surgical device slides.However, it has been discovered that there is a need in the art for aguidewire that more easily navigates tortuous bodily lumens and allowssurgical devices to slide thereover more easily (i.e. with less frictionbetween the device and the guidewire) while providing tactility to theuser to allow adequate control and placement of the guidewire within thebodily lumen.

Embodiments of the instant disclosure address a weakness of bothindustry standard guidewire types to provide both tactile feedback andeasy device passage. No currently available guidewire provides both ofthese features. Rather, hybrid guidewires offer improved tactilefeedback to increase control and positioning accuracy within the bodilylumen, but do not allow for easy passage of surgical devices thereover.On the other hand, hydrophilic guidewires offer easy passage of surgicaldevices thereover, but lack tactile feedback. Consequently, theembodiments of the instant disclosure address a need in the artcurrently unmet.

It is a first aspect of the present invention to provide a guidewirecomprising a hydrophilic surface coating encasing a core and a metalcoil along a longitudinal length of the hydrophilic surface coating toform a distal closed tip, the metal coil circumscribing the core along apredetermined length, the core extending longitudinally beyond the metalcoil in both a proximal direction and a distal direction, where aproximal section of the guidewire includes a hydrophobic surfacecoating.

In a more detailed embodiment of the first aspect, at least a portion ofthe core extending in the distal direction beyond the metal coilincludes a silane coating. In yet another more detailed embodiment, thecore includes a frustroconical shape that extends beyond the metal coilin the distal direction. In a further detailed embodiment, the silanecoating is separated from the hydrophilic surface coating by athermoplastic polymer layer. In still a further detailed embodiment, thethermoplastic polymer layer is radiopaque. In a more detailedembodiment, the thermoplastic polymer layer comprises a polycaprolactonebased polyurethane elastomer. In a more detailed embodiment, thepolycaprolactone based polyurethane elastomer comprise tungsten loadedpellethane. In another more detailed embodiment, the core is coated inan epoxy primer. In yet another more detailed embodiment, the epoxyprimer comprises a mixture of an epoxy resin, an epoxy polyamine adduct,and a glycidyl ester. In still another more detailed embodiment, theepoxy primer is adjacent the hydrophobic surface coating.

In yet another more detailed embodiment of the first aspect, an overalllength of the guidewire is between ten and two hundred inches. In yetanother more detailed embodiment, the core has a median diameter betweenapproximately 0.035 inches and 0.038 inches. In a further detailedembodiment, the distal closed tip is atraumatic. In still a furtherdetailed embodiment, the core is at least one of solid and hollowed. Ina more detailed embodiment, the core comprises an alloy of nickel,titanium, and cobalt. In a more detailed embodiment, the core includes across-sectional shape comprising at least one of circular, oblong, andrectangular. In another more detailed embodiment, the core includes atapered section. In yet another more detailed embodiment, the coreincludes a frustroconical section. In still another more detailedembodiment, the guidewire further includes a silane coating interposingthe core and the hydrophilic surface coating.

In a more detailed embodiment of the first aspect, the silane coating isspaced from the hydrophilic surface coating by a thermoplastic polymerlayer. In yet another more detailed embodiment, the thermoplasticpolymer layer is radiopaque. In a further detailed embodiment, thethermoplastic polymer layer comprises a polycaprolactone basedpolyurethane elastomer. In still a further detailed embodiment, thepolycaprolactone based polyurethane elastomer comprise tungsten loadedpellethane. In a more detailed embodiment, the core is coated in anepoxy primer in the form of two ring-shaped coatings spaced apart fromone another. In a more detailed embodiment, each of the two ring-shapedcoatings is no greater than ten inches in length. In another moredetailed embodiment, the metal coil comprises stainless steel. In yetanother more detailed embodiment, the metal coil has a radialcross-section that is rectangular in shape.

It is a second aspect of the present invention to provide a guidewirecomprising: (a) a first section comprising a core, a hydrophilic layer,and a polymer layer interposing the core and the hydrophilic layer; (b)a second section comprising the core, the hydrophilic layer, and a metalcoil interposing the core and the hydrophilic layer; and, (c) a thirdsection comprising the core and a hydrophobic layer, where thehydrophilic layer and the hydrophobic layer comprise an exterior surfaceof the guidewire; and the hydrophobic layer comprises more than ninetypercent of the exterior surface.

It is a third aspect of the present invention to provide a method offabricating a guidewire comprising: (a) mounting a metal coil over acore so that the metal coil circumscribes the core along a predeterminedlength, the core extending longitudinally beyond the metal coil in botha proximal direction and a distal direction; (b) encasing the metal coiland a majority of the core in a hydrophilic exterior surface layer so adistal tip of the guidewire is closed; and, (c) forming a hydrophobicexterior surface over a minority of the core.

In a more detailed embodiment of the third aspect, the method furtherincludes shaping the core to create a tapered distal segment. In yetanother more detailed embodiment, the method includes shaping the coreto create the tapered distal segment include grinding the core to removematerial from the core. In a further detailed embodiment, the methodincludes forming the hydrophobic exterior surface over the minority ofthe core includes heat shrinking a hydrophobic tube over the minority ofthe core. In still a further detailed embodiment, the hydrophobic tubeis heat shrinked over a proximal-most section of the core. In a moredetailed embodiment, the hydrophobic tube comprisespolytetrafluoroethylene. In a more detailed embodiment, the methodfurther includes applying an epoxy primer to the core so as to interposethe core and metal coil. In another more detailed embodiment, the epoxyprimer is applied to form two rings around the core that are spacedapart from one another. In yet another more detailed embodiment, themethod further includes heat treating the applied epoxy primer to bondthe core to the metal coil where the epoxy primer was applied. In stillanother more detailed embodiment, the method further includes applying asilane primer to a distal most portion of the core.

In yet another more detailed embodiment of the third aspect, the methodfurther includes curing the applied silane primer via a heat treatment.In yet another more detailed embodiment, the method includes encasingthe metal coil and a majority of the core in the hydrophilic coatingalso includes encasing the silane primer.

It is a fourth aspect of the present invention to provide a method ofusing a guidewire comprising: (a) inserting a closed distal tip of aguidewire into a bodily lumen, the guidewire comprising a hydrophilicsurface coating encasing a core and a metal coil along a longitudinallength of the hydrophilic surface coating to form a distal closed tip,the metal coil circumscribing the core along a predetermined length, thecore extending longitudinally beyond the metal coil in both a proximaldirection and a distal direction, wherein a proximal section of theguidewire includes a hydrophobic surface coating; (b) repositioning theguidewire within the bodily lumen to reach an end location for theclosed distal tip while receiving real-time images from a radiationimager that depict a relative location of the distal tip with respect toa section of the bodily lumen; (c) inserting a medical instrument overthe guidewire post the distal tip reaching the end location; (d)carrying out a medical procedure using the medical instrument; and, (e)withdrawing the guidewire from the bodily lumen post insertion of themedical instrument.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exterior profile view of an exemplary guidewire fabricatedin accordance with the instant disclosure.

FIG. 2 is a cross-section taken along the longitudinal direction of theexemplary guidewire of FIG. 1 .

FIG. 3 is a longitudinal cross-sectional view of the first section ofthe exemplary guidewire of FIG. 1 .

FIG. 4 is a radial cross-sectional view of the first section of theexemplary guidewire of FIG. 1 , taken at line A-A.

FIG. 5 is a longitudinal cross-sectional view of the second section ofthe exemplary guidewire of FIG. 1 .

FIG. 6 is a radial cross-sectional view of the second section of theexemplary guidewire of FIG. 1 , taken at line B-B.

FIG. 7 is a longitudinal cross-sectional view of a portion of a thirdsection of the exemplary guidewire of FIG. 1 .

FIG. 8 is a radial cross-sectional view of a portion of the thirdsection of the exemplary guidewire of FIG. 1 , taken at line C-C.

FIG. 9 is a longitudinal cross-sectional view of a portion of the thirdsection of the exemplary guidewire of FIG. 1 .

FIG. 10 is a radial cross-sectional view of the portion of the thirdsection of the exemplary guidewire of FIG. 1 , taken at line D-D.

FIG. 11 is a longitudinal cross-sectional view of a portion of the thirdsection of the exemplary guidewire of FIG. 1 .

FIG. 12 is a radial cross-sectional view of the portion of the thirdsection of the exemplary guidewire of FIG. 1 , taken at line E-E.

FIG. 13 is an exemplary process flow diagram for fabricating anexemplary guidewire in accordance with the instant disclosure.

FIG. 14 is an exemplary process flow diagram for using an exemplaryguidewire disclosed herein in accordance with the instant disclosure.

DETAILED DESCRIPTION

The exemplary embodiments of the present disclosure are described andillustrated below to encompass exemplary guidewires, methods offabricating the same, as well as methods of using the same. Of course,it will be apparent to those of ordinary skill in the art that theembodiments discussed below are exemplary in nature and may bereconfigured without departing from the scope and spirit of the presentinvention. However, for clarity and precision, the exemplary embodimentsas discussed below may include optional steps, methods, and featuresthat one of ordinary skill should recognize as not being a requisite tofall within the scope of the present invention.

Referencing FIGS. 1 and 2 , a first exemplary guidewire 100 isconfigured for insertion into a bodily lumen such as, withoutlimitation, a ureter. In this exemplary embodiment, the guidewire 100may have an overall length of between ten to two hundred inches. Forpurposes of exemplary explanation only, the guidewire 100 will bedescribed as having an overall length of approximately fifty-nineinches. The guidewire 100 may have a circular or rounded cross-sectionalprofile (i.e., axial profile) taken perpendicular to the dominantlongitudinal dimension (i.e., the lengthwise dimension). By way ofexample, an outside diameter of the guidewire 100 may be between 0.025to 0.10 inches, and more specifically range between 0.0345 and 0.0385inches. For purposes of exemplary explanation only, the guidewire 100will be described as having generally a circular axial profile with anoutside diameter between approximately 0.035-0.038 inches. By way ofexample, the guidewire 100 may be comprised of differing layers andconstituents along its length that may correspondingly change thecross-sectional make-up of the guidewire. As a result, the followingdiscussion of the guidewire 100 constituents is broken down into aseries of guidewire sections that are seamlessly coupled to one anotherbetween a distal tip (inserted first into the bodily lumen) and theproximal end.

Referring specifically to FIGS. 1-4 , a first section 110 includes adistal tip 112 and a predetermined length extending proximally away fromthe tip. By way of example, the distal tip may comprise an atraumatictip, though this is not a necessity. The first section 100 comprises acore 114 that may be solid or partially hollowed. In exemplary form, thecore 114 comprises an alloy of nickel, titanium, and cobalt having acircular axial profile that need not be constant along the axial lengthof the first section 110. More specifically, the core 114 may taper inshape so that, in the case of a circular or rounded axial profile, theoutside circumference of the core material decreases between theproximal portion of the first section 110 and the distal tip 112. By wayof further example, the core 114 may have a circular axial profile thatgradually tapers until reaching a blunt distal end 116, therebyembodying a frustoconical shape.

A second constituent of the first section 110 comprises a silane coating120 applied over the exterior of the core 114 that is operative toencapsulate the distal end 116. In this exemplary embodiment, the core114 may be dipped in liquid silane that cures to form the coating 120.Alternatively, the core 114 may be sprayed with a liquid silane thatdries to form the coating 120. Those skilled in the art will understandthe plethora of techniques that may be used to form a silane coating 120over a core 114, with such techniques being omitted only in furtheranceof brevity, and each of which shall fall within the scope of the instantdisclosure. By way of example, the silane coating 120 may comprise anysilane composition operative to promote adherence between the core 114and a top coating 124.

By way of example, the top coating 124 may comprise a radiopaquethermoplastic polymer operative to encapsulate the distal end 116 of thecore material, as well as the silane coating 120. By way of furtherexample, the top coating 124 may comprise a polyester polycaprolactonebased polyurethane elastomer such as, without limitation, tungstenloaded PELLETHANE, available from The Lubrizol Corporation. By makingthe top coating 124 radiopaque, the first section 110 is relativelyimpenetrable to the transmission of radiation, thus creating a clearlyvisible darkened image when within the field of view for X-ray,fluoroscopy, CT, or other radiation imaging technologies.

The top coating 124 is itself encapsulated by a surface coating 126. Inexemplary form, the surface coating 126 may comprise a hydrophiliccoating, where the distal end of the coating comprises the distal tip112 of the guidewire. In exemplary form, the first section 110 may havea length of approximately two inches.

Referring to FIGS. 1, 2, 5, and 6 , the first section 110 may beseamlessly bonded to a second section 130 that is operative to form atransition between a third section 150 and the first section 110. Thesecond section 130 may include three of the same constituents as thefirst section 110, namely the core 114, the top coating 124, and thesurface coating 126, in addition to a metal coil 132 positioned adjacentto the top coating 124. In exemplary form, the metal coil 132 providesmicro ridges and valleys when covered by the top coating 124, which isoperative to provide increased traction or a coefficient of frictiongreater than the first section. As will be discussed in more detailhereafter, a heat treatment may be applied to the guidewire 100resulting in a portion of the top coating 124 diffusing beyond the firstsection 110 and into the second section 130 between the coil 132 turnsand the core 114. In this fashion, post heat treatment, a thin portionof the top coating 124 sits atop and/or protrudes between the turns ofthe coil 132.

In this exemplary embodiment, the metal coil 132 may comprise stainlesssteel (such as a 304V alloy) or any other biologically inert/compatibleor acceptable metal or metal alloy. The turns of the metal coil 132 mayhave a helical shape with an outer diameter substantially constant andranging between 0.025 to 0.10 inches, and more specifically rangebetween 0.0345 and 0.0385 inches. The metal comprising the turns of thecoil 132 may have a circular, rounded, or other shaped cross-section. Byway of example, the coil turns may have a square or rectangularcross-section. In other words, the metal wire comprising the coil 132,before it is coiled, may have a square or rectangular cross-section. Inexemplary form, the second section 130 may have a length ofapproximately 0.2 inches.

Referencing FIGS. 1, 2, 7, and 8 , post the second section 130 is thethird section 150. This third section 150 may include the core 114 and,rather than having a silane coating 120 as in the first section 110, mayinclude an epoxy primer coating 160 over top of the core 114 along apredetermined length of a distal portion and the proximal most portion.By way of example, this predetermined length may be 0.5 inches so that adistal portion has a 0.5 inch length epoxy primer coating 160 and theproximal most 0.5 inch length includes the epoxy primer coating 160directly over the core 114. In exemplary form, the epoxy primer coating160 may comprise a mixture of an epoxy resin, an epoxy polyamine adduct,and a glycidyl ester. The same metal coil 132 that may be present in thesecond section 130 may be present in the third section 150 and overliethe epoxy primer coating 160 (where present) and otherwise overlie anddirectly contact the core 114. The same surface coating 126 may beapplied over the metal coil 132.

Referencing FIGS. 9 and 10 , the vast majority of the length of thethird section 150 may omit the epoxy primer coating 160. In such aconfiguration, the core 114 is circumscribed by the metal coil 132,which itself is covered with the surface coating 126 to encapsulate themetal coil and core material. In this configuration, the metal coil 132may be free floating over the core 114 thereby allowing the metal coilto move independent of the core 114. In exemplary form, the thirdsection 150 may have a length of approximately 51 inches.

Referencing FIGS. 1, 2, 11, and 12 , a fourth section 180 may seamlesslyabut the third section 150 opposite the second section 130. This fourthsection 180 may include the same core 114, yet omit the epoxy primercoating 160, the metal coil 132, and the surface coating 126. Inexemplary form, the core 114 of this fourth section may include ahydrophobic coating 190. This hydrophobic coating 190 may comprise anynumber of hydrophobic materials such as, without limitation,polytetrafluoroethylene (PTFE). In exemplary form, the hydrophobiccoating 190 may be applied in the form of a PTFE tube that isheat-shrinked to precisely circumscribe and contact the adjacent core114. In this exemplary embodiment, the fourth section may have a lengthof 4.9 inches. By way of further example, the first section 110 has alesser coefficient of friction than the second section 130, where thesecond section has a lesser coefficient of friction than the fourthsection 180.

Turning to FIG. 13 , an exemplary process 200 for producing theexemplary guidewire 100 is provided. Specifically, fabrication of theforegoing guidewire 100 may commence at step 202 by forming the core 114into a desired shape. By way of example, a predetermined length of core114 (such as 59 inches), which length may vary depending upon thedesired length of the guidewire, may be unwound from a spool of corematerial. The core 114 may have a generally uniform cross-section alongits dominant longitudinal length that may be circular, oblong, oranother shape. In exemplary form, the uniform cross-sections of the coremay range between 0.015 and 0.090 inches in diameter and, morespecifically, may range between 0.0240-0.0275 inches in diameter. Thisgenerally uniform cross-section may be supplemented by longitudinallengths that are tapered or otherwise varied to change the overall widthof the guidewire 100 and/or to change the proportion of thecross-section occupied by the core 114. By way of further example, thecore 114 may comprise a cylindrical shape having a circular axialprofile that is tapered along a predetermined length to provide afrustoconical tip. This tapering process may be part of step 202 and maybe carried out by grinding or any other material removal process. Inexemplary form, the tapering may occur on a 2 inch distal end of thecore 114.

Post forming the core 114 into a desired shape in step 202, a subsequentstep 204 may include formation of the hydrophobic coating 190 at aproximal end of the core material. Specifically, a hydrophobic tube ofPTFE may be positioned to circumscribe a proximal section (or end) ofthe core 114. Post positioning of the PTFE tube around the core 114,heat is applied to the tube, which causes the tube to shrink and formfit to the exterior of the core 114, thereby providing a hydrophobiccoating 190. In exemplary form, the resulting hydrophobic coating 190may have a radial thickness ranging between 0.005 and 0.05 inches. Morespecifically, the hydrophobic coating may have a radial thickness ofapproximately 0.013 inches.

Before, during, or after formation of the hydrophobic coating 190 aboutthe core 114, at step 206, the metal coil 132 is slid over a distal endof the core 114 until a proximal end of the metal coil abuts an intendedor actual distal end of the hydrophobic coating 190. The length of themetal coil 132 may be chosen so that a distal section of the core 114 isnot circumscribed by the coil. In exemplary form, the metal coil 132 maycomprise any biocompatible metal or metal alloy including, withoutlimitation, stainless steel 304V. It should also be known that thecross-section of each metal strand wound to form the coil may have across-sectional shape other than circular or oblong. For example, themetal strand may have a square or rectangular cross-sectional shape.

Before, during, or after positioning the metal coil 132 around the core114, at step 208, an epoxy primer coating 160 is applied topredetermined portions of the core 114 to eventually interpose the coreand metal coil. During step 208, an epoxy primer may be applied to apredetermined length of the core 114 (such as, without limitation, 0.5inches) immediately distal to the intended or actual end location of thehydrophobic coating 190, as well as to a more distal location locatedabout six inches (about 15 centimeters) from the distal tip of the core.Post application of the epoxy primer coating 160 and the metal coil 132,a heat treatment step 210 may be carried out to bond the metal coil 132to the core 114 by curing the epoxy primer coating 160.

At step 212, a distal-most section (e.g., about two inches) of the core114 may be dipped in a silane primer or have a silane primer sprayapplied thereto. Heat is applied to the wet silane composition postapplication to cure the silane and form a coating 120 over the distalcore 114.

After the silane coating 120 is formed in step 212, a top coating step214 may be carried out. In this step 214, a polymer coating 124 may beapplied over the silane coating 120 by dipping or spraying a liquidpolymer composition to the distal-most section (e.g., about two inches)of the core 114. Alternatively, the polymer coating 124 may be in theform of a tube wrapped in a disposable peel-away heat shrink tube, whichare both applied over the silane coating 120. In exemplary form, thepolymer composition may comprise a radiopaque material, when cured, suchas, without limitation, tungsten loaded pellethane. Post application ofthe polymer coating 124 over the silane coating 120, a heat treatmentmay be carried to bond the polymer coating 124 to the silane coating 120and core 114. During such a heat treatment, portions of the polymercoating 120 may flow into communication with and under the metal coil132 and become entrained within the coils, thereby bonding the polymercoating 124 to the metal coil 132. Post heat treatment, in the contextwhere a peel-away heat shrink tube is utilized, the disposable heatshrink tube may be peeled away to leave only the polymer coating 124 asthe outermost surface of the guidewire 100.

At step 216, a hydrophilic surface coating 126 is applied over thecomplete length of the polymer top coating 124 and the metal coil 132,but need not be applied over the hydrophobic coating 190. Application ofthe hydrophilic surface coating and any resulting cure sub-steps may befashioned to arrive at a guidewire with an atraumatic distal tip 112. Inexemplary form, the hydrophilic surface coating may have a radialthickness of between 0.0001 and 0.001 inches and, more specifically havea radial thickness of approximately 0.0005 inches.

Turning to FIG. 14 , an exemplary process 300 for using the exemplaryguidewire 100 is disclosed. Specifically, the distal tip 112 may beinserted at step 302 into the bodily lumen of a mammal. Post insertionof the distal tip 112, an operator of the guidewire 100 may twist andmanipulate the guidewire at step 304 to force more of the guidewiredeeper into the bodily lumen until the distal tip reaches a desiredposition within the bodily lumen. As part of twisting and manipulatingthe guidewire, a fluoroscopic unit (known to those skilled in the art)may be utilized by the operator at step 306 to provide visualindications of the location of the distal tip 112 relative to the bodilylumen.

As discussed previously, the first section 110 of the guidewire 100includes a radiopaque polymer coating 124 (e.g., tungsten loadedpellethane) that, under fluoroscopy or other radiation-based imager,shows up as a darkly shaded object contrasting against the lightershades of the bodily lumen. Consequently, the operator of the guidewire100 can redirect the guidewire in real-time responsive to real-timeimages generated from a radiation-based imager. This same imager may beused by the operator to identify an appropriate termination location forthe distal tip. Upon reaching the appropriate termination location forthe distal tip within the bodily lumen, the operator may move to step308 to thread the appropriate surgical instrument over the guidewire100.

In exemplary form, the surgical instrument threaded over the guidewire100 may vary greatly depending upon the bodily lumen the guidewire islocated within as well as the intended surgical procedure. Consequently,any surgical device that may be threaded over a guidewire is implicatedherein and within the scope of the intended use of being threaded overthe instant guidewire 100. By way of example, in the context of thebodily lumen comprising a ureter, the surgical instrument may comprise aureteroscope. By way of further example, in the context of the bodilylumen comprising a ureter, the surgical instrument may comprise at leastone of a ureteral stent and a ureteral access sheath. It should beunderstood that the exemplary guidewire 100 is not limited to urinaryapplications. Instead, the exemplary guidewire 100 may be used incirculatory procedures including, without limitation, angioplastyprocedures. It should be noted that contrary to conventional wisdom, thehydrophilic surface coating 126 provides a lower coefficient of frictionfor sliding surgical instruments thereover than a comparable hydrophobiccoating.

Before, during, or post the surgical procedure, an operator of theguidewire 100 may pull or otherwise withdraw the guidewire through thebodily lumen including withdrawal of the distal tip 112 from the bodilylumen at step 312.

It should also be noted that the exemplary guidewire 100 may bedisposable or may be used repeatedly for the same or different surgicalprocedures.

Following from the above description, it should be apparent to those ofordinary skill in the art that, while the methods and apparatuses hereindescribed constitute exemplary embodiments of the present invention, theinvention described herein is not limited to any precise embodiment andthat changes may be made to such embodiments without departing from thescope of the invention as defined by the claims. Additionally, it is tobe understood that the invention is defined by the claims and it is notintended that any limitations or elements describing the exemplaryembodiments set forth herein are to be incorporated into theinterpretation of any claim element unless such limitation or element isexplicitly stated. Likewise, it is to be understood that it is notnecessary to meet any or all of the identified advantages or objects ofthe invention disclosed herein in order to fall within the scope of anyclaims, since the invention is defined by the claims and since inherentand/or unforeseen advantages of the present invention may exist eventhough they may not have been explicitly discussed herein.

What is claimed is:
 1. A guidewire comprising: a hydrophilic surfacecoating encasing a metal coil and a majority length of a core to form adistal closed tip, the metal coil circumscribing the core along apredetermined length, the core extending longitudinally beyond the metalcoil in both a proximal direction and a distal direction, wherein aproximal section of the guidewire includes a hydrophobic surface coatingover a minority length of the core.
 2. The guidewire of claim 1, whereinat least a portion of the core extending in the distal direction beyondthe metal coil includes a silane coating.
 3. The guidewire of claim 2,wherein the silane coating is separated from the hydrophilic surfacecoating by a thermoplastic polymer layer.
 4. The guidewire of claim 3,wherein the thermoplastic polymer layer is radiopaque.
 5. The guidewireof claim 4, wherein the thermoplastic polymer layer comprises apolycaprolactone based polyurethane elastomer.
 6. The guidewire of claim5, wherein the polycaprolactone based polyurethane elastomer comprisetungsten loaded pellethane.
 7. The guidewire of claim 1, wherein thecore includes a frustroconical shape that extends beyond the metal coilin the distal direction.
 8. The guidewire of claim 1, wherein the coreis coated in an epoxy primer.
 9. The guidewire of claim 8, wherein theepoxy primer comprises a mixture of an epoxy resin, an epoxy polyamineadduct, and a glycidyl ester.
 10. The guidewire of claim 8, wherein theepoxy primer is adjacent the hydrophobic surface coating.
 11. Theguidewire of claim 1, wherein an overall length of the guidewire isbetween ten and two hundred inches.
 12. The guidewire of claim 1,wherein the core has a median diameter between approximately 0.035inches and 0.038 inches.
 13. The guidewire of claim 1, wherein thedistal closed tip is atraumatic.
 14. The guidewire of claim 1, whereinthe core is at least one of solid and hollowed.
 15. The guidewire ofclaim 1, wherein the core comprises an alloy of nickel, titanium, andcobalt.
 16. The guidewire of claim 1, wherein the core includes across-sectional shape comprising at least one of circular, oblong, andrectangular.
 17. The guidewire of claim 1, wherein the core includes atapered section.
 18. The guidewire of claim 1, wherein the core includesa frustroconical section.
 19. The guidewire of claim 1, furthercomprising a silane coating interposing the core and the hydrophilicsurface coating.
 20. The guidewire of claim 19, wherein the silanecoating is spaced from the hydrophilic surface coating by athermoplastic polymer layer.
 21. The guidewire of claim 20, wherein thethermoplastic polymer layer is radiopaque.
 22. The guidewire of claim21, wherein the thermoplastic polymer layer comprises a polycaprolactonebased polyurethane elastomer.
 23. The guidewire of claim 22, wherein thepolycaprolactone based polyurethane elastomer comprise tungsten loadedpellethane.
 24. The guidewire of claim 1, wherein the core is coated inan epoxy primer in the form of two ring-shaped coatings spaced apartfrom one another.
 25. The guidewire of claim 24, wherein each of the tworing-shaped coatings is no greater than ten inches in length.
 26. Theguidewire of claim 1, wherein the metal coil comprises stainless steel.27. The guidewire of claim 1, wherein the metal coil has a radialcross-section that is rectangular in shape.
 28. A method of fabricatinga guidewire comprising: mounting a metal coil over a core so that themetal coil circumscribes the core along a predetermined length, the coreextending longitudinally beyond the metal coil in both a proximaldirection and a distal direction; encasing the metal coil and a majoritylength of the core in a hydrophilic exterior surface layer so a distaltip of the guidewire is closed; and, forming a hydrophobic exteriorsurface over a minority length of the core.
 29. The method of claim 28,further comprising shaping the core to create a tapered distal segment.30. The method of claim 29, wherein shaping the core to create thetapered distal segment include grinding the core to remove material fromthe core.
 31. The method of claim 28, wherein forming the hydrophobicexterior surface over the minority of the core includes heat shrinking ahydrophobic tube over the minority of the core.
 32. The method of claim31, wherein the hydrophobic tube is heat shrinked over a proximal-mostsection of the core.
 33. The method of claim 31, wherein the hydrophobictube comprises polytetrafluoroethylene.
 34. The method of claim 28,further comprising applying an epoxy primer to the core so as tointerpose the core and metal coil.
 35. The method of claim 34, whereinthe epoxy primer is applied to form two rings around the core that arespaced apart from one another.
 36. The method of claim 34, furthercomprising heat treating the applied epoxy primer to bond the core tothe metal coil where the epoxy primer was applied.
 37. The method ofclaim 28, further comprising applying a silane primer to a distal mostportion of the core.
 38. The method of claim 37, further comprisingcuring the applied silane primer via a heat treatment.
 39. The method ofclaim 37, wherein encasing the metal coil and a majority of the core inthe hydrophilic coating also includes encasing the silane primer.